N. rachovii

I can perhaps add a few comments to the discussion on N. rachovii
that you may find interesting:
1. The N. rachovii Beira '91 population was collected by John
Rosenstock (in 1991, of course). John managed to get a number of the
wild males back to Denmark alive but only one female made it. The
stock presently in the hobby stem from this single female.
2. The N. rachovii Beira '98 represents a recent semi-commercial
collection, specimens of which I was able to import to Canada with
the help of some friends in Africa. A number of pairs of these were
distributed at the BAKA West Coast weekend show and also at the AKA
convention.
While both of these populations have the location name "Beira"
(please note the correct spelling !) my information suggests that
they are not from the exact same location. It would probably be
advisable NOT to cross the two strains.
3. N. rachovii "KNP Black" is from the Kruger National Park in South
Africa. There has only been one introduction of this population into
the hobby and that was from a single pair collected by John Vermaak
in 1984. There is only one known locality for this population,
although a couple of translocations were (unsuccessfully) attempted.
This fact, and also because of the prolonged droughts that the KNP
has been subject to in recent years, has placed this population in a
rather precarious position in the wild. Any hobbyist who has this
population should devote some special attention to it because the
chances of it being re-collected (at least for introduction into the
hobby) are very slim. Incidentally, N. orthonotus "KNP Red" was
collected from the same locality at the same time and also introduced
into the hobby by Vermaak.
There is, therefore, only one "strain" of N. rachovii "KNP Black" in
the hobby. This fish has never been common in the hobby and a few
years ago, I suspect that I was the only person still maintaining it.
I am quite sure that by the end of 1993 it was no longer in Europe
and in May, 1994 I took 12 pairs and eggs to the DKG Convention where
they were distributed. I would assume that the "DKG" strain that Dale
Deck refers to represents fish derived from these specimens that I
took to Europe.
4. The incubation time for eggs of N. rachovii Beira can be highly
variable depending on specific conditions in your breeding tanks. As
Barry has already pointed out, if you harvest the peat from the tanks
infrequently then anaerobic conditions will develop in the peat and
this will cause the eggs to go into a prolonged resting phase. This
is certainly the case in my fish-room and I commonly hatch out N.
rachovii Beira after incubation periods of more than a year. My
records indicate a personal minimum of 4 months and a maximum of 26
months.
The fact that eggs from wild Nothos commonly (but not always) develop
in a shorter time than eggs from subsequent generations is a
phenomenon that we have observed with regard to the many of wild
Nothos that have been collected during the past 10 years. I am unable
to offer an explanation for this.
5. The eggs of N. rachovii "KNP Black" take, on average, even longer
to incubate than do those of the Beira population of this species and
this is in keeping with the fact that the KNP region of South Africa
is relatively dry (or at least can be subject to prolonged periods of
drought). For example, a few days ago I hatched out fry of this
population from peat that I have had in storage for more than two
years and the previous batch of this population that I had were
hatched from eggs that were a bit over 3 years old ! While sorting
through the spawnings a few days ago (trying to find one with eyed
eggs) I came across one spawning that was loaded with eggs, which
were all clear and undeveloped, and yet the spawning was 3 years and
3 months old ! So, if you work with this population be patient and be
careful about discarding peat.
6. Returning for the moment to the matter of incubation times being
controlled (to some extent) by conditions in the peat while still in
the tank. If anaerobic conditions result in prolonged incubation
times (which I personally prefer and regard as more "natural") then
it follows that well oxygenated peat in the tank will result in
relatively short incubation times. For those of you out there who are
impatient, try using a box filter, without the lid, as the peat
container in the spawning tank, allowing air to bubble gently up the
filter stem. You may have to place the peat on a piece of fine mesh
to prevent it from being drawn up the filter stem. This will cause
aerated water to be continually drawn down through the peat and I
think you will be surprised at what it will do to shorten the
incubation times, especially if you use a fairly coarse peat and
harvest it at 1-2 week intervals.
7. One final point concerns the moisture content of the peat. Keeping
the peat relatively moist may speed up incubation a bit but don't
overdo this. If the peat is wet to the point where it packs together
as a relatively solid mass then you will find incubation times can
also be prolonged as a result. This can be a problem with very fine
peat especially. I have observed this over the years and my
explanation (theory) is that when peat is "waterlogged" and
compacted, the eggs will be in contact with water more than they will
with air and that water will definitely be oxygen deficient (mainly
because the peat will undergo mild decay in the bags, bacterial
action, etc.). Certainly, air circulation in the peat will be
severely restricted under such conditions. Peat in storage should be
loose, initially, at any rate - eventually the bags will deflate and
the peat will compact to a degree but it is the early stages of
incubation that are important with respect to oxygen content.
__________________________________________________
Brian R. Watters
University of Regina
Regina, Saskatchewan S4S 0A2, Canada
Ph: (306) 584-9161 (home); (306) 585-4663 (work)
Fax: (306) 585-5433
E-mail: bwatters at sk_sympatico.ca